Field of the Invention
There are many previously known accumulating lift and carry conveyor systems for transferring parts, such as piston connecting rods, in a manufacturing environment. These previously known accumulating conveyor systems typically comprise a pair of elongated stationary rails which are spaced apart and parallel to each other. These stationary rails are spaced apart from each other by a distance such that the stationary rails can support opposite sides of the conveyed items.
A transfer rail assembly is disposed in between the stationary rails. The transfer rail assembly includes a pair of elongated transfer rails which are spaced apart and parallel to each other. Unlike the stationary rails, the transfer rails are movable between a raised and lower position, as well as also between a forward and a retracted position. In their raised position, the transfer rails engage and lift the conveyed parts up above the stationary rails. Thereafter, the transfer rails are moved to their forward position, simultaneously moving the conveyed parts forwardly along the conveyor system. Thereafter, the transfer rails are moved to their lower position again re-depositing the conveyed parts on the stationary rails. The transfer rails are then moved to their retracted position, and the above cycle is repeated.
In order to move the transfer rail assembly between its raised and lower position, typically a pair of drive arm assemblies are disposed between the conveyor frame and the transfer rail assembly. One end of each drive arm assembly is pivotally connected to the frame while its upper end abuts against the bottom of the transfer rail assembly. Consequently, as the drive arm assemblies pivot from a first to a second position, the drive arm assemblies simultaneously vertically displace the transfer rail assembly from its lower position to its raised position.
In order to move the transfer rail assembly between its forward and retracted position, typically a drive plate is connected to the bottom of the transfer rail assembly along its center line. This drive plate is then longitudinally displaced between the forward and the retracted position by a motor, typically employing an eccentric cam.
In order to ensure that the transfer remain horizontal during their vertical displacement and thus preventing any cocking of the transfer rails, the drive arm assemblies are typically connected together by a pair of elongated link arms such that one link arm extends along each side of the drive plate. Furthermore, it has been previously necessary to utilize a pair of link arms in order to prevent excessive torsional loads on the drive arm assemblies that might otherwise be caused if a single off-center link arm were used.
While these previously known conveyor systems have operated satisfactorily, the necessity to provide two elongated link arms is relatively expensive, thus increasing the overall cost of a conveyor system. Furthermore, since the motor which drives the drive arms between their first and second pivotal positions must also both longitudinally and vertically displace the link arms, the use of two link arms between each adjacent pair of drive arm assemblies necessarily increases the motor power requirements for the conveyor system and also the overall cost of the conveyor system.